Oscillograph.



L. T. ROBINSON.

OSGILLOGRAPH.

APPLIOATION FILED IAB. 13, 1905.

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L. T. ROBINSON.

OSCILLOGBAPH. APPLICATION FILED MAB. 1a, 1905.

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OSGILLOGRAPH. APPLIUATION FILED 112111.13, 1905.

Patented Apr. 27, 1909.

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L.l T. ROBINSON.

' osGILLoGRAPH. APPLIOATIONFILED MAB.. 13. 19.05.

Patented Apr. 27, 1909.

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Inventor I Lewis T. Robinson. bym@ Vltnesgses um /f/.

, /To all whom 'it may con-cern:

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LEWIS T. ROBINSON,

OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC r COMPANY, A CORPORATION OF` NEWYORK.

oscILLoGRAPH.

Specification of Letters Patent.

PatentedApril'?, 1909.

Application le'd March 13, 1905. Serial No. 249,744.

Be it known'that I, LEWIS T. RoiaiNsoN, a citizen of the United States, residing at Schenectady, county of Schenectady, State `of New Yrkrhave invented certain new and useful Improvements in Oscill graphs,y of whichthe following is a yspecific tion.

This invention relates to instruments for indicating or measuring rapid changes in the position or value of a 'varying quantity or element.

More particularly, my invention relates to instruments Vof the type commonly known as oscillographs for obtaining curves of the instantaneous values of voltage and current or other dharacteristics which may be derived therefrom.

The instrument consists of a reflecting galvanometer of extremely high eriod and suitably'damped, placed, in a lig t-tight box in which is anl opening providedwith a shutter lfor admittin light rays from an arc lamp 01 other suitab e so rce. Lenses and mirrors maybe arranged in position to `concentrate the rays on the mirror of the galvanometer from which they are reected onto either a photographic film Afor making apermanent record of therosciliations' or a suitable screen in order'that the varying values may be observed.

In the'preferred formof my invention I employ three refiecting galvanometers and means whereby the rays from the mirror of each one ca n be focused on the same point so as to take-three waves simultaneously sho'wmg each 1n its proper phase relation to the others.

The novel features of my invention will be ldefirlit'ely indicated in the claims appended ere o.

`-"The details of' construction and the mode vv'of o eration 4oflmy im roved osoillograph will e better understoo( by reference to the AfollQWiIigujdesoription,1 taken in connection with thej. accompanying drawings, which 4showA theI preferred embodiment of my in- 'ventlon` 1 u thedrawingaFigure 1 is a plan view of -the instrument; FigsZ B, a sectional elevationfof the same;` F1g.'3 is a sectional elevag .tion of Lthe film .and shutter operating mechaDSm Fig; 4 1s. a plan view of the prisms and-slits;vv 1

g.' 5' is a' front l view of one' of `the vibratorsand' its chamber; Fig isa sectional elevation of the same; Figf7 is a plan view of the supporting member of the vibrator; Fig. 8 is a 'detail vlew of the prisms and their supports FigLgis a perspective view of the moving element; vlFlg. vl0 is an elevation of the combined hand and electromagnetic shutter mechanism shown in dotted lines in Fig. 2; Fig. 11 is a sectional View at right angles .to the plane of Fig. 10 and Fig.

. 12 shows three alternating current curves traced simultaneously on one film by the 1nstrument, one curve being a close approximation to a sine curve, 'the Second-bemg ir-` peak of the curve, and the y regular near the third being very lrregular.

Referring to the drawings, l indicates a light-tight box having a removable cover 2 and doors in the sides which may be opened in order to adjust the parts. .In the end of the boxen a raised platform 3 are mounted three galvanometers. The magneticfield for each of the galvanometers is supplied by a strong electro-magnet 4. These Ithree electro-magnets are arranged side by side and two of the energizing coils v5 5 are each wound about the a d1acent legs of two of the magnets. 'The magnets are thus arranged in a very compact manner.l Beneath the platform 3 is a resistance 6 which. may be connected in circuit withthe coils 5, when necessary, to obtain the proper energizing current. Also, the coils of the magnets may be connected in series and arallel for this samepurpose. Between t e legs of each magnet 4 is supported aclosed chamber 8 carrying the vi rator which forms the moving element of the galvanometer- In order that the osition of the vibrator may be adjusted I fiirm trunnions 7 on the side of each chamber 8 and provide openingsin "the ends 'of the legs ofthe ma nets to receive these trunnions. Each. c amber: has

an extension 9 at its lower end, and a screw 10 having a knurled head passes 'throu h a pivoted nut in standard 11 on the plat orm 3 and into` a threaded opening in a nut swiveled in the extension'Q so that by turning the screw the chamber and the various parts thereof are rocked on a horizontal axis. In Ithe sides of each chamber- 8 are ole-pieces 12 12 which carry the lines of orce of the magnet and on which the trunvnionsA 7 are formed. a These pole-pieceshave -relatlvely large outer\surfaces in contact with the legs of the'magnet, as shown in Figs. 5 and 6, and they are tapered so that the adjacent surfaces are comparatively small and the air-gap between these surfaces is a very narrow one. The ole-pieces 12 12 thus concentrate the lines ot forceV in a very narrow iield and therefore the eld is a very strong one. Another important advantage obtained by this construction is that in adjusting the vibrator carried within the chamber 8 on a horizontal axis the auxiliary pole-pieces 12 12 are adjusted with it so that the relation of the vibrator and the'magnetic field is in no way changed. In the top of the chamber is a circular opening and mounted for movement about the edge of this opening is a holder 13, a portion of the periphery of which is cutto orm a worm-wheel wlth which meshes a worm 14 on a shaft 15 provided witha knurled head. The vibrator is detachably secured on the holder 13 and therefore when the shaft 15 is rotated, it operates through the gearing to/ turn the holder and the v ibrator carried thereby on a vertical axis.

The arts of the ,vibrator are assembled on a cyllindrical supporting member 16 and a threaded screw 17 having a knurled head extends through this member and into a threaded opening in the holder 13 to detachably secure the vibrator in place thereon. Secured to the back of the supporting member 16 is a frame 18 which at lts lower end carries two blocks 19 of insulating material, preferably ivory, over which the wires of the movable member of the galvanometer extend. A rod 20 passing loosely through the member 16 and the two blocks 19 carries a small pulley 21 at its lower end. This pulley is supported on the rod 20 from only one side, as shown in Fig; 5. At its upper'end rod 20 is secured to a follower 22 aving an opening therethrough.

A threaded shaft.23,lrotatable in bearings in the frame 18 and the member 16 and having a knurled head, passes loosely lower 24 is threaded on this shaft.

through the follower 22 and a second fol- Secured to the followers 22 and 24 are the two members of a telescoping casing 25 in which is a spiral spring 25 (Fig. ,2) the ends of which are attached to the two members of' the casing. Thusl the spring in the casing 25 acts on the follower 22 to force the rod 20 ldownward through the opening in the mem- Mounted on member 16 are two bindingposts 26 and 27 suitably insulated by a strlp of ivory 28 to whichar'e attached the terminals of a loo ed conductor 2 9, referably a strip of thin r1 bon conductor, w 'ch forms the moving element of theinstrument. In the member 16 is a radial opening, as shown in Fig. 7. The loop 29 is mounted in position by soldering one end-to the vbindei'aaev ing post- 26, then drawing the wire through the radial opening in member 16, then carrying it down over the blocks 19-19, around pulley 21, back over blocks 19' 19 and through the slit -in member 16, and then soldermg its other end to the binding-post 27. Shallow notches are cut in the ivory blocks 19 to hold the two lengths of the conductor parallel to each other and very close together and at the same time prevent them from coming in actual contact. This loo ed conductor 29 is made of a material of ow resistance but of considerable elasticity, so thatit will be springy and have a high rate of vibration when put under tension. Heretofore it has been considerednecessary to use for this purpose a conductor of phosphorbronze or steel because of its greater strength but the high resistance causes considerable heating ofthe conductor and a gradual creeping of the beam of light across the scale,

A so that the beam of light does not come back to zero when the current is cut off. I have found, however, that a looped conductor of silver or of 'silver alloyed with a small amount of some other metal can be made sufficiently strong for the purpose and its lower resistance is or great advantage as the heating is so slight that it produces practically no eii'ect. In practice it is frequently necessary to use the instrument for obtaining curves on a circuit carrying a very large current. To do this the conductor 29 is connected in. parallel to a shunt inserted in the main line. If the conductor is made of phosphor-bronze or steel the` shunt in the main line must be vvery large and a large amount of energ is lost therein, where-as by making the con( uctor of silver or other material having a very low resistance the size of the shunt can be greatly reduced and the great decrease in the voltage drop between the terminals of the shunt effects a corresponding decrease in the energy loss therein. ,The spring 25in the casing 25, tending to push the rod 20 downward, holds the looped wlre under tension. Turning the shaft 23 by its knurled head moves the follower 24 up or down and thus changes the tension ofthe spring 25 on 'the'loop 29. The inner member ofthe casing 25 may be graduated to assist the operator in securing the desired tension on the loop. The member and frame 1 8 form a conductor support which can be moved back from the po e pieces when the screw 17 is loosened, since the clearance between the frame 18 and llO the casing 8 is great enough, as shown in Fig.

6, to permit the conductor to be moved transverselyLof the axis of the pole pieces and brought out .toward the center of the .casing 8, after which the conductor support can beremoved longitudinally of the casing Without any danger of injuring the conductor. The pulley 21 is mounted out of alinement with the axis of the pole pieces, as

shown in Figs. 6 and 9, and if desired, the conductor can be moved longitudinally from between the pole pieces without the pulley from the chamber if desired, its part-s are all perfectly accessible and the tension of the loop can be observed and regulated without removing the vibrator from the chamber. The tapering pole-pieces 12 12 concentrate the lines of force of the electro-magnet on the ortion of the loop 29 between the two bloc rs '19 19 and midway between these two blocks a small mirror 30 1s secured to the two lengths of the wire by cement. detachable plate 30 closes the front of the vibrator chamber and is provided with an opening over the mirror 3() in which a lens or glass 31 is mounted. When the instrument is to be used the vibrator chamber -is filled to a level above the mirror 30 with a damping liquid such as castor oil to dampen -the oscillations of the mirror.

It will be seen that when .the vibrator is removed from its chamber, the two lengths of the looped conductor 29 are perfectly accessible on all sides about the point where the mirror 30 is secured thereto. In instruments of this type as heretofore constructed the vibrator has not been removable independently of the partswhich are mounted close to the mirror such as the pole-pieces inserted in the sides of the chamber, so that it is extremely difficult to mount a new mirror 1n place owing to the very limited space in which to work. On account of the delicacy of the parts, securing a new mirror 30 to the two lengthslof the looped conductor is diflicult even under the best conditions but by so constructing the vibrator that when removed from its chamber the conductor is accessible on all sides about the point where the mirror is secured thereto this can be much more readily accomplished.

Between adjacent galvanometers a sheet 29 insulating material is inserted as shown 1n 1g. 1. that it will withstand a high potential, preferably as much :ts-5000 volts, so that the several galvanometers are effectually insulated one from another.y I consider this a feature of considerable importance as in practice it is often found desirable, and sometimes almost necessary in order to get accurate curves, to carry to the several galvanometers currents diiering greatly in potential, and this can be done with safety when the galvanometers are individually insulated one from another.

This sheet is of such a thickness In the box 1 is al1-opening 31 normally closed by a shutter 32 inside the box secured on a shaft 33 which also carries the armature 34 of a pair of electro-magnets 35. Thus when the magnets are energized the armature is rocked on its shaft and the shutter 32 is moved away from the opening, and when the magnets are denergized, a spring 36 brings the shutter back so as to close'the opening as is shown in Fig. 10. Extending through'the box is a shaft 37 carrying an arm 38. This shaft may be turned by hand from outside the casing to bring the arm 38 into engagement with a finger 39 depending from the shaft 33 so as to move the shutter,i

away from the opening 31. The arts may be left in this relation, friction in tiie bearing of shaft 37 serving to hold them against the tension of spring 36. The light entering the opening 31 when the shutteris moved away is yreceived by three prisms 40 (Figs. 2.and 8),

each carried by a post 41 held on a su port 42 which is secured on a standard within the box 1. In each of the posts 41 is an enlargement forming a ball 43. Plates 44 are secured tothe support by screws 45 and the posts 41 are each held between the support and one of the plates 44. In the support and the lates'are slight depressions to receive'thelballs 43. The prisms are thus supported in aV manner permitting adjustment in any direction, a button being provided on the lower end of each post 41 for this purpose.` lThe su port 42 for these prisms is arranged at a slight angle so that the iiist prism does not obstruct the passage of the rays of light to the third prism and the second one is arranged above the level of the first and the third vona holder 42 which is bent so as not to obstruct the rays to the third prism, so that each of the three prisms receives the rays of light through the opening 31 direct from an arc lamp or other suitable source 4located outside the box 1. j

' The prisms 40 reiect the rays upon the mirror of the galvanometer through adjustable slits located one in front of each ofthe three prisms. .Each of th`ese adjustable slits 47 is carried on a post 48 which extends down through an o ening in a support mounted on a raised plat orm 46, and at its lowerend is provided with a pin 49 by which the slit may be angularly adjusted. A spring 50 coiled about the post 48 keeps the slit in any position to which itis moved, a collar 50- securedon post 48 serving to hold the post against u ward movement. These adjustable slits ave been 'constructed heretofore from solid cylindrical blocks by cutting a slot with straight sides therethrough. With such a construction even though the slit be painted black, the rays of light are reflected to some extent by the walls of the slot. I avoid this by making the slit from a tube by cutting slots of a width less than the inner diameter of the tube in the walls of the tube at diametrically opposite points, as shown in y is turned on its Figs. 2 and 4, thereby forming a slit or passage with concave Walls, havin r its greatest cross-section midway between the ends. In this way, rays which enterthe slit at one side at somewhat of an angle strike on the concave wall and are not reflected out through the other end of the slit, and the only rays of light coming through thc adjustable slit are the direct rays. means of the pin 49 more and more Vof these direct rays may be cut off and the width of the beam of light thus adjusted. To further shut off allrays of light but the useful ones, a screen 51 is secured to the support for the magnets 4 in which are three openings 52, one for each beam from the prism 40 to the mirror of the galvanometer corresponding thereto.

From the mirror the rays are reflected back through the opening 52, either upon a film for taking a photographic record or upon a mirror 53 by which they are reflected di- `rectly upward upon a ground glass 55 or A other translucent sheet mounted over an" opening in the cover of the box 1. The drawings show the parts in position for the rays of light from the galvanometer mirror to be refiected by mirror 53 upon ground glass 55. vWith theparts thus arranged it will be seen that as the mirror of the galvanometer turns back and forth on-a vertical axis the spot of light on the mirror 53 will move back and forth across the mirror and the spot refiected by the mirror 53 on the ground glass 55 will move from side to side. In order to obtain a curve of the oscillations, the mirror 53 is supported on pivots and means are provided for rocking 1tS so as to give a movement of the spot of light up and down on the ground glass 55.

In order to get an accurate curve" the fre quency of the rocking movement of mirror 53 should bear va definite ratio to the frequency of the oscillations of the mirror of the` galvanometer, and I therefore employ a synchronous motor 56 secured to the box 1 on the outside thereof and connected in the samecircuit with the loop of the Ualvanometer to effect this movement. The shaft of this motor extends through the box 1 and on its inner end carries a cam 57. Rigidlysecured to the mirror 53 is an arm 58 with which the cam 57 cooperates. A spring 59 is secured to arm 58 and normally holds it down upon the surface of thevcarn 57.- Thus when motor 56 drives cam 57 the mirror 53 pivots andzthen brought back to its initial posltion. Turning the mirror in v this waynloves the spot of light lengthwise ony the ground glass and the movement of the galvanometer mirror moves the spot of light from' side to side, so that a curve 1s projected upon glass 55. To avoid confusion the spot By turning the slit by! z of light should not show as the mirror is bel ing returned to its initial position by spring l 59 as the cam Vpasses under arm 58, and I j therefore provide a shutter 57 on the shaft j 56 of the motor 56 outside the box 1 which.

j covers the o ening 31 for the rays of light l from the arc amp while the return of mirror il 53 is being effected. The other end of the r spring 59 is secured in a block on the end of a lever 60 which is loose upon a )ivoted shaft 61. A handle 62 is secured to this shaft, and I has a slot formed therein through which a I: pin in the lever 60 having a lockingnut on .1 its end extends. Rigidly secured to the f shaft 61 are two arms 64, between which are secured the pivoted mirror 53 and a lens 54 to concentrate the rays of light. Above the lens 54 is a shutter 65 carried by a shaft 66 with its free end resting u on the top of the lens. Secured to the sha t 66 is a crank 67 and a link 68 is pivotally connected at one end to this crank and at the other end to a crank 69 on a shaft 70 which carries a shutter 71 similar to the shutter 65.

In the position of the parts shown in F ig. 2 the rays of light reflected from the galvanometer mirror are concentrated by the lens 54 on the mirror 53 and are reflected upward thereby on the ground glass 55. The curve showing the osclllations may be observed on the ground glass or a sheet of thin paper may be placed over the ground glass and the curve traced thereon. If it is desired to take a photographic record of the oscillations the handle 62 is pulled back. This turns shaft 61 and thus raises the arms 64 which carry upward with them the lens 54 and mirror 53. In its upward movement lens 54 raises the shutter 65 thus turning shaft 66 which by means of the crank 67, link 68 and crank 69, turns shaft 70 and 'thus raises shutter 7l. When the edges of the shutter and 7l c ome together the opening for the light rays up closed. vStrips 72 (F 1g. 2.) are arranged at the sides of the shutters so as to insure a complete closure of this openin parts are in this position, the Iight rays are reflected by the mirror of the onto a lens 73 by which they are concen-A trated and from which they pass through a narrow o ening inthe back of the box 1.] Detachab ysupported on the back of the box is a light-tight casing 74 in which is a drum I carried by a shaft 75. This drum `or holder is provided withmeans for holding a photo- I graphic film or other sensitized sheet tightly thereon. Secured to the back of thebox is a frame 76 forming a bearing for a shaft 77 carying a pulley 78 Y able source of power. On the end of shaft 77 is a crank 79 which coperates withla in 80 on theshaft to rotate the drum whic carries the photographic i The position of arranged to receive a belt which the shaft 77 is driven from any suitto the-ground glass 55 is y When the galvanometer accomplishing this, one of whic i opens the shutter at` the instant the end of the film passes the slot in the back of the box 1, and

the other of which opens it at any art irrespective `of the 'position of the m. The

v former is useful when niaking investigations in which the events are recurring or their bed 77 is a threadedsleeve 81 of insulating mal thereon. The other end of the wire is con- 'nected to the shaft 77 so that the wire is electhe ginning known or under control, and the latter whenthe time of the event is not under control, such as the blowing of a fuse or the opening of a circuit-breaker. On the shaft terial. A wire 82 has one end embedded in this sleeve and extends around the sleeve one complete turn in the bottom of the thread trically connected to the frame 76. Vertically movable in suitable guides is a rod 83 carrying an arm 84 at its up er end oirthe under side of which is a tootii 8-5. Secured to rod 83 is another arm 86 to which is attached one end of a spring 87 the other end of which is secured to a pivoted lever 89. Also secured on rod 83 is a latch 88 adapted to enter. a notch in the lever 89. A spring 90 is arranged topress the lower end of lever 89 toward the rod 83. A link 91 is connected to the lower end of lever 89 and in its end is an eye to facilitate connecting it to acircuitbreaker or any other device by which it is to be operated. A lever 92 having an Aoperating handle is pivoted s o that its end is di- 1e tly below the lower end of rod 83. When it is desired to take a photographic recordol' the oscillationsof the galvanometer mirror and to make the record begin at one end of the photographic film and end at the other,

ink 91 is pulled to the right in Fig. 3 either by Vhando`r by attaching it to any device which is .to operate-it. This draws the lower end of` lever 89 to the right againstthe tension of spring 90, thus releasing the latch 88 and spring 87 then draws the rod 83 down- Ward in its guides until the tooth 85 on the under side of arm 84 enters the threads on sleeve 81. As the shaft 77 is continuously rotating the rod- 83 is turned in its guides as the tooth 85 travels along on the sleeve 81. Then the tooth 85 engages the wire 82 arm 84 and the frame 76 are electrically connected and this' closes circuit through a battery and the coils of the magnet35 which rocks its armature 34 tomove the shutter 32 away from the opening 31. When shaft 77 has made one complete revolution the tooth 85 rides off of the wire 82 and this circuit .is broken, whereupon the spring 36 draws the shutter 32 back over the opening 31. The light rays' from the source outside the box 1 have thus been allowed to enter the box and have been reflected by the mirror of the alvanometer upon the photographic film uring one complete revolution of the drum which carries the film and thisperiod began as the beginning of the film passed the slot in the back ofthe box 1 and ended as the end of the iilm passed this slot. After the record has been taken, the handle of lever 92 is depressed and the rod 83 is thus raised until thev tooth 85 is out of engagementwith the sleeveV 811 rod 83 in its guides to brin the parts back to their former positions, the atch 88 serving to hold them in this position by catching inthe notch in lever 89.

Pivoted on `the sigle of the frame 76 is a lever 93 on thef side of which is pivotally mounted a roller 94. A portion 95 of the periphery of this roller is made of insulating material and a brush 96 su ported on the lever 93 below roller 94 but insulatedtherefrom bears on the periphery of the roller. A

spring 97 is arranged to turn the lever 93 on its pivot in a direction to bring the roller 94 into engagement with a roller 98 on shaft 77. A pivoted lever 99 carries a pin 100 in its upper end which extends into the path of movement of lever 93, a spring 101 being arranged to move the parts to this position. Secured to the lower end of lever 99 is a stud 102 having an eye in its end by which the lever may be connected with a circuitbreaker or any other device which is to control the time of taking the record. 4When it is desired to take a photographic record and the time of the event that is to be recorded is not under control, the operation of the device whose effect is to be noted is made to pull the lower end of lever 99'to the right in Fig. 3: "This carries the pin 100 out of the path of movement of lever 93 and spring 97 turns the lever on its pivot so as to bring roller 94 into engagement .with roller 98. The roller 94 is thus made to rotate and the brush 96 moves off the insulating segment 95 and upon the metal portion of the roller. This c oses the circuit of the electro-magnet 35 as before and this circuit is retained closed while shaft 77 is making one complete revolution when brush 96 vmoves upon the insulating segment 95 again. In this position adepression in the roller 94 (Fig-s. 1 and 2) comes opposite the roller 98 and roller 94 comes to rest.

bring pin 100 again into the ath of move-- ment Tof lever Roller 94 is thus carried The lever 93 is then pushed back by its operating handle and spring. y101 l/Vhen this occurs spring 87 turns the Cir . parts'in: the position shown in Fig. 2 the l this mirror reflects the rays upward upon the loop 29.l When the mirror 53 is being re- 'upon the loop 29, one side of which carries A closes the opening 31 in box 1.

away from roller 98 and may be turned by ,I hand to its former position as shown in Fig. l 2. A record is thus obtained covering the l entire film but this record may begin at any l portion of the film and run to the end and then from the other end down to a point l close to where it began.

The operation of the device will be readily f5 understood from theforegoing description. The terminals of the circuit, the energy characteristics of which are to be examined, are connected to the binding-posts 26 and 27 so that the current liows through the loop 29. i The coils 5 of the electro-magnets are conl nected in circuit so that a strong magnetic field is produced between the pole-pieces 12 12. The influence of the magnetic field current in one direction and the other side carrying current inthe opposite direction, causes the two sides of the loop to move'in opposite directions in the magnetic field and y as the current alternatesl the two wires will l move .back and forth. This oscillates the mirror 30 on a vertical axis. The strength of' the field and the lightness of the parts and the delicate way in which they are mounted causes the mirror to respond to every variation in the current flowing in the loop. The damping liquid fills the chamber 8 and thus entirely surrounds the mirror 30 the viscosity of the liquid should be just sufficient to make the indications accurate. VWhile adjusting the parts the shaft 37 is turned by hand. from outside the box 1 so as to move the shutter 31 and the light from an arc lamp or other suitable source` enters the box through this opening and is reflected by the prisms 40 upon th`e mirrors of the three galvanometers. The Width of the beams of light may be adjusted by the adjustable slits 47; the prisms 40 may also be adjusted to bring them into the exact position desired. The vibrator of each one of the three galvanometers can be adjusted on both a vertical and horizontal axis by means oli the screws 10 and 15 to direct the beam of light from the mirror 3() in the exact direction desired. With the 'f ters 65 and 71.

vibrator should be adjusted so that the beam of light isreflected upon the lens 54 which s concentrates the rays upon the nirror 53 and ground glass 55'. The circuit of the motor 56 is closed and the motor drives cam 57 which operates the arm 56 to rock mirror 53 on its pivots. Thus as the galvanometer mirror turris on a vertical axis and the mirror 53 is turned on its horizontal pivots a curve is (plrxpjected upon 1' the glass 55- correspon g exactly to the variations of the current in the turned to its initial position the shutter 57l The curve may be observed upon the glass 55 or if desired a paper' may be laid over the glass and the curve traced thereon. 'By moving vthe lever 60 independently of the handle 62 thc tension of spring 59 may be varied. If it is desired toy take a photographic record of the curve the handle 62 is pulled back thus turning shaft 61 and raising the arms 64 which carry with them lens 54 and mirror 53 and as the lens 54 moves upward it closes the shut- The rays of light are then reflected by the galvanometer mirror upon the lens 73 which concentrates them upon a photographic film in the casing 74, the latter being provided with a narrow opening and a door forclosing the opening light-tight. To take the record this door is opened and after taking the record the door isagain closed so that the casing may be removed from the box 1 and carried to a dark room without admitting light to the film. f S5 If the event to be recorded on the film is recurring or its time under control, the record is taken by pulling the link 91 to the lright in Fig. 3 by hand or in any other suitable mauner and spring 87 pulls the arm 84 down upon the sleeve 81. W hen the finger 85 makes 'contact with the wire 82, the circuit of the magnets controlling the shutter 32 is closed. and the magnet opens the shutter and holds it open during exactly one revolution of thc film-carrying drum.' `The wire SQ yis so positioned onthe sleeve 81 that the shutter is opened just as the beginning of the film passes the slot in the casing 74 so that the record extends from one end of the film to the other. After the record is taken, the'y handle of lever 92 is pushed down to restore the parts to their initial positions. It' the time of the event to be recorded is not under control, as for instance the blowing of a fuse or the o en ing of a circuit-breaker, the movement o the parts the effect of which is to be recorded is made to pull the stud 102 to the right in Fig. 3. This releases the lever 93 and spring 97 turns` it on its pivot :in til roller 110 94 is brought into engagement with roller 98. Roller 94 is thus caused to rotate bringing brush 96 into engagement with the metallic part ofthe roller and thus closing the circuit of the magnet controlling the shutter 32, as before. 'lhe length of the metallic portion of roller 94 is'such that this circuit 1s retained closed during exactly one Arevolution of shaft 77 and the film-carrying drum. The record thus taken extends over the entire film but may begin at any point throughout the length thereof. W hen roller 94 has turned. far enough to bring the brush 96 again upon the insulatin segment 95, a depressed portion of the ro ler comes opposite the roller 98 so that the latter is no longer driven b I roller 94. Lever 93 is then pressed back by its handle and is held in the retracted .position by pin 100, and roller 94"'is turned ack by-hand to the position shown in thelo drawing sc as to be ready for a repetition of l ing an opening therein to admit a beam of the operation.- As there vare three galvanometers, three curves can be obtained at the same time. of voltage or current in each phase of multihase circuit. simultaneously. Also, since t e vibrators are adjustable in all directions, the beams of light from the three'mirrors 30 may be focused on the same point and then the curves obtained give the phase relation of each with respect to the other.

I do not Wish to be understood as limited to the recise construction which I have herein siiown and described, as many modifications can be made' therein all of which I consider Within the scope of my invention and aim to cover. in the claims appended hereto.

What I, claim as new and desire' to secure by Letters Patent ofthe United States, is,

1. An .o lscillograph'y comprising a lighttight boxfa refiecting galvanometer therein, means for obtaining a visible indication of' the movements of the galvanometer mirror, means for obtaining a photographic indication of said movements, and means operative Without opening the box for changing from one manner of obtaining indications to the other.

v 2. An oscillograph comprising a box havin an o ening therein to admit a beam of lig t, a p urality of reflecting galvanometers therein, means for directing'a beam of light upon the mirror of each ga vanometer, means for obtaining a visible indication of the movements of the galvanometer mirrors ,l means for obtaining a photographic indication of said fmovements, and means for changing from one manner of obtaining indications to the other.

3. An oscillograph comprising a box having an opening therein to admit a beam of light, a reiiecting galvanometer in the box, a prism in the box opposite said opening to reect the light on the mirror of the galvanometer, a post on Which the prism is supported, a ball formed in the post, plates between which said ball may be clamped to hold the prism and permit adjustment of its osition, and means cooperating With said ga vanometers for obtainlng an indication of the movements of the alvanometer mirrors.

4. An oscil ograph com )rising a reflecting` galvanometer, means for irecting a beam of light upon the mirror of the galvanometer, a rotatable shutter for regulating the width of the beamiarranged to admit light through a passage shaped to have the greatest cross section near the middle and thereby prevent access to the galvanometer of rays reflected from said beam of light, and means coperating with said galvanometer for obtaining an indication of the movements ofthe galva- Vnometer mirror. l

5. An oscillograph comprising a box hav- Itis thus possible to take curvesy light, 4a plurality of reflecting galvanometers` ,'therein, means for directing a beam of light upon the mirror of each galvanometer, a tube having a slot therethrough adjustably arranged in the beam of the light for regulating the Width thereof, and means coperi ating with said galvanometers for obtaining an indication of the movements of thevv galvanometer mirrors.

6. An oscillograph comprising a ,lighttight box, a plurality of reflecting galvanom- I eters therein, means for dlrectlng a beam of light upon the mirror of each galvanometer, a translucent screen, a photographic device, and means operative when the box is closed for directing the oscillating beam either to the screen or the vice.

'2. An oscillograph comprising a lighttight box, a plurality of reflecting galvanometers therein, means for directing a beam of llght upon the mirror of each galvanometer, a translucent screen, a photographic device, a mirror for reflecting the beam of light from the galvanometer upon said sheet, and means for moving the mirror into orout of the path of the beamof light whereby theI screenand the photographic device are alternatively thrown into and outof operation.

8. An oscillograph comprising a lighttight box, a plurality of reflecting galvanometers therein, means for directing a beam of light upon the mirror of eachgalvanometer, a translucent screen, a photographic device, a mirror for reflecting the beam of light from the galvanometer upon said screen, a shutter, and means vfor moving the mirror out ofthe path of the beam and closing the shutter whereby the screen is rendered inoperative /and the hotographic device operativo- 9. An osci lograph comprising a lighttight box, a plurality of reflecting galvanom- 'eters therein., a translucent screen, a mirror for reflecting thet beams of light from the galvanometers upon the screen, means for rockingI the mirror, a photographic device, and means for moving said mirror into or out ofthe. path of the beam of light whereby the screen and the photographic device are alternately thrown into and out of operation.

10. An oscillograph comprising a lighttight box, a plurality of reflecting galvanometers therein, a translucent screen, a mirror for reflecting the beams of light from the photographic de- A galvanometers upon the screen, means for giving the mirror a rocking movement the frequency of which bears a definite ratio to Y the frequency of the oscillations of the mirror of thegalvanometer, a photographic device, and means for moving said mirror into or out of the path ofthe beam oflight whereby the screen and the photographie device are alternately thrown into and out of operation. 11. An oscillograph comprising a light- 35 moving said mirror into or out of the -60' pieces, a support for said mirror'and nous motor arranged to rock said mirror, a

photographic device, and means for moving said mirror into and out of the path of vthe beam of light whereby the screen and the photographic device are alternately thrown t into and out of operation.

12. An oscillograph comprising a lighttight box, a plurality of reilecting galvanometers therein, a translucent screen, a mirror Jfor reflecting the beams of light from the galvanometers upon the screen, means for rocking the. mirror, means for shutting 'off the beams of ,light from the screen while the mirror is rocking in one direction, a photographic device, and means for moving said mirror into or out of the path of the beam of 'light whereby the screen and the photo- .graphic device are alternately thrown into and out of operation.

13. An oscillograph comprising a lighttight box, a plurality of reiiecting galvanometers therein, a translucent screen, a mirror for reflecting the beams of light from the galvanometers upon the screen, means for givv ing the mirror a rocking movement .thefre- :i0 quency of which bears a deniteratio to the frequency ofk the oscillations of the galva: nometer, means for shuttin off the beams of light whilethemirror is roc ing in one direction, a photographic device, and means for path of the beam oip light whereby the screen and the photographic device are alternately thrown into and out of operation.I

14. In an oscillograph, the combination 40 with means arranged to coperate with a galvanometer to obtain an indication, of a refleeting galvanometer comprising a movable f mirror, a support for said mirror ad'ustable about two perpendicular axes'whic adjusting said sup ort. j

15. In an oscil ograph, the combination with means arranged to coperate with a galvanometer for obtaining an indication, of a reflecting galvanometer comprising a mirror mounted to rotate, a support forsaid mirror mounted to rock on an axis which intersects the axis of rotation of' themirrxr at a point in the mirror, and adjusting 'means for rockin vsaid suport.'

\ 16.` nanosc ograph, a reflecting galvanometer com rising a movable mirror and `pole pieces a jacent thereto, a magnet with its poles in` metallic contact With said'poe o e piec'zc'v'sA mountedbetween the poles' offpthe magnet to rock about an axis "transverse to the axis of movement of tMmirror. and slide 'said pole pieces over the polesoithe magnet,

inter-Vv 45. sect at a point in said mirror, and means for ity of moving elements, a plurality of electromagnets, one'leg of each magnet being arranged ad jacent to one leg of another magnet with a single energizing coil on each of said ,pairs of adjacent magnet legs, and means cooperating with said galvanometers for obtaining an indication. l

18. In an oscillograpli, the combination `with a plurality of galvanometers having moving systems arranged side by side, each moving system comprising pole pieces and a currentcarrying conductor movably mounted bctween said pole pieces, of insulation between said moving systems to permit the a plication of widely different potentials to t e current carrying conductors of adjacent systems.

19. In an oscillograph, a plurality of galvanometers havingmagnets and moving systems arranged side by side and strips of insulating material between adjacent magnets and moving systems, and common means cooperating With said galvanometers for obtainin a simultaneous indication therefrom.

20. n an'oscillograph, a relectin galvanometer comprising a magnet, a c amber pivotally supported on the legs thereof, a moving elementl for said galvanometer mounted in'said chamber at right angles to the pivot of the chamber, means for rocking .the chamber and the moving element carried thereby about the pivot of the chamber, and` means cooperating with said galvanonieter for obtainin an indication.

21. In an osci lograph, a reilecting galvanometer comprising a magnet, a chamber, means for horizontally pivoting said chamber, a moving element for said galvaiiometer supported in said chamber, means for adjusting said moving element on a vertical axis, means for rocking said chamber and the moving element carried thereby on a hoiizontal axis, and means coperating with sai 22. In an oscillograph, a relectino-galvanometer comprising a magnet, a ciamber pivoted between the legs of the magnet, polepieces located in the sides ofthe chamber and in contact with the legs of the .magnet thro Uhoiit the range of movement'of the cham er-about its pivot, said pole-pieces having a relatively large surface on the outgalvanometer for obtaining an indicav tion.l

.side of the chamber and being contracted so as tol concentrate-the magnetic lines in a nar- I row gap between their adjacent surfaces, a

moving element for said galvanoineter r'e- Y-movably mounted in said gap, and means cooperating Withsaidgalvanometer for obtain ing an indication.

23. In an oscillograph, aY reiectinggalva-:-

nometer comprising a magnet, a chamber supported between the le'gs of the magnet,I I o e-pieces located in the sides of the chamer,/ trunnions formed on the pole-pieces, openings in the legs of the magnet to receive said trunnions, an adjusting device for rocking said chamber on said trunnions, a moving /element for the galvanometer in said chamber in the gap between said poleieces, and means cooperating with said ga Vanometel` for obtaining an indication.

24..In any oscillograph, a reiiecting galvanometer comprisin a ma net, a chamber located between the egs o the magnet, polepieces in the sides of the chamber in contact with the legs 'of the magnet, a moving element mounted in the chamber and arranged to be2 removable therefrom independently of saidv pole-pieces, and means cooperating with said galvanometer for obtaining an indication. A

25. In an oscillograph, a alvanometer including means for establis ing a magnetic field', a moving element mounted in the e'ld zfc'om rising a supporting member, a rod exten lng downward therefrom, a pulley on the lower end of the rod, a looped conductor extendinfy around the pulley and having its ends electrically connected to parts a ove said member, a reflecting device carried by said conductor, means above said member to press said rod downward, and meanspcoperating with said galvanometer for obtaining an indication.

cluding means for establishing a magnetic iield, a moving element mounted in the field comprising a supporti 0' member havin av ntlllr glot central opening there ough and a s leading to sai opening, a rod extending Ydownward -from the member, a .pulley pivotally mounted on said-rod near its ldwer end and supported fromV only one side, and a loo ed conductor passinoP around said pulley 45 an extending up' throng the opening 1n said member, reiiecting means carried by said conductor, 'andmeans coperating with said galvanometer for obtaining an indication.

27 .,In an oscillograph, a plurality of al van'ometers com risin a plurality of osc' la.

tory mirrors an con uctors on which they are mounted, insulation between adjacent conductors a plurality ofeld magnets insun lated from one another the fields of` which cut the conductors, and means cooperating with said galvanometers for obtaining an indicatlon. y A

28. In an oscillograph, a galvanometer comprising means for roducinl al magnetic4 6'0 field, a conductor capab e of osc ato motiement in said held, a mirror mounted t ereon, a chamber for damping liquid inclosing the conductor, a support for the conductor capable 4of withdrawal from said chamber, the

moving element) and its support being so re- 26. In an oscillograph, e galvanometer inlated that a free space surrounds the conductor to permit ready mounting'of the mirror, and means coperating with said galvanometer for obtaining an indication. 29. An oscillograph comprising a lighttight box, a reflecting galvanometer therein, a holder, a sensitized sheet thereon, means for rotating the holder, and means for regulating the exposure of the sensitized sheet to the oscillating beam from the galvanometer to begin and end at the two ends of theV sensitized sheet. y

30. An oscillograph comprising a lighttight box, av reiiecting galvanometer therein, a older, a sensitized sheet thereon, means for rotating the holder, 'and means for regulating the exposure of the lsensitized sheet to the oscillating beam from the galvanometer to lastduring only'one revolution of the holder. 85 Y 31. An oscillograph comprising a lightl tight box, a reflecting galvanometer therein, a older, a sensitize sheet thereon, means forrotating the holder, a shutter, and means 'for keeping the shutter open during only a 90 single -Z-rotation of the holder.

32. An oscillograph comprising a lightti ht box, areiecting galvanometer therein, aiolder, a sensitized sheet thereon, means for rotating the holder, a shutter, and means for opening the' shutter vwhen the end of the sheet is in position to receive .the indication and closing it after a single revolution of the helder. 4

33. Anoscillo a h comprising a reflecting galvanometer, aA o der for a sensitized sheet, actuating means for moving the holder, and mechanism operating in deiinite relation to said actuating means, for obtainin an indication of the movements of the a vanometer mirror on said sheet during te definite part of the movement of said holder.

34. An oscillograph comprising a f ll'ghttight box, a reflecting galvanometer therein, a holder, a sensitized sheet encircling the holder, means for rotating the. holderand t means for admitting light to the mirror of said vreflecting galvanometer during only one revolution of the holder.

35. An oscille ra hcomprising areflecting galvanometer, atlio der for a sensitized sheet actuating means for moving the holder, and means for admitting a beam of light from .the galvanometer mirror to said -sheet -when one end of thesheet is in a redetermined position and cutting off the lght when the other end of the sheet reaches said position.

36. An oscillograph comprising a lighttight box, a refiecting galvanometer therein,

a sensitized sheet, means for obtaining on said 'sheet' an indication of the movements of the galvanometer mirror, and electricallyl operated means contilling the time `of said indication.

oscillograph @mprisiag a light-'13o l lend ol' said sheet is in a holder, a sensitized' sheet thereon, means 'for rotating the holder, means for obtaining on said sheet an indication of the movements of the galvanometer mirror, and means con- 'trollingthe time of said indication operative to start the indication instantly or' when the position to receive the indication.

38. An oscillograph comprising a lighttiglit box, a reflecting galvanometer therein, a holder, a sensitized sheet thereon, means for rotating the holder, means for obtaining on said sheet an indi-cation of the movements of the galvanometer mirror, and means controlling the time of said -indication operative to stait the indication instantly or when the end of said sheet is in position to receive the indication and to discontinue the indication when the holder has made one revolution.

39. An oscillogiaph comprising a lighttight box, a reflecting galvanoiiieter therein, a holder, a sensitized sheet thereon, means for moving the holder, a shutter controlling the admission of light to the galvanometer mirror, a magnet controllingithe shutter, and means for energizing the magnet during a denite movement of the holder.

40.. An oscillograph comprising a lighttight box, a reflecting galvanorneter therein, a sensitized sheet, a holder for supporting the same inu the path of thebeam of light from the galvanometer mirror, means for rotating the holder, a shutter controlling the admission of light to the galvanometer mirror, an electromagnet to o erate the shut-ter, and means for yclosing tlie magnet circuit when the end of said sheet is in position to receive the indication and holding it closed during one revolution of the holder.

41. In an oscillograph, a reflecting gala looped conductor carried by said support to extend through said opening at said point with its ends held by said terminals.

42. In an oscillograph, a reflecting galvanometer comprising a support havii-igan o ening therethrough-and a slot extending t `rough said member to said opening, terminals mounted on said su-p ort on opposite sides of' said opening, a ro extending parallel to the axis ofsaid opening, and a looped conductor passing around thel free end of said rod and through said opening with its ends engaged by said terminals.

43. In an oscillograph, a reflecting gallvanometer comprising a supporting member having an opening therethrough extending from the periphery of said member-to a-point near the middle thereof, terminals adjacent .said point onone side of said'rnember, a'rod era-467 extending from the other side of said member, and a loopedconductor assing around the free end of said rod and) through said openings with its ends secured to said termi-- nals.

44. In anoscillograpli, a reflecting galvanonieter comprising a support, aloopcd conductor attac ied to said support at two points, a mirror secured to said conductor,

ccess to every pai't of the mirror.

45. lii an oscillograph, a reflecting galvanonieter comprising a sup` ort, terminals on said support,'insulating ocks on said support, a rod slidably` mounted on said support, a pulley'on one end ol said rod, atension device mounted adjacentsaid terminals and connected to the other end of the rod to move it longitudinally, `and a looped conductor with its ends connected to said tei'- minals assing over said blocks and around said Epulley.

46. In an oscillograph, -a galvanometer comprising a support, terminals on said su port, a conductor connected to said termina s, means for resiliently holding the conductor under tension, and a device adjacent said terminals for controlling the action ol'. said means.

47. In an comprisinga support, terminals on said support, a looped-conductor with its ends yconnect'ed to said terminals, ya resilient device carried by said support: for -holding said conductor undertension, and means mounted on said support adjacent said terminals for controlling-the action of said resilient device onthe conductor.

oscillograph, a galvanometer J 48. In an oscillograph, areflecting galva-- 5 nometer comprising a support, terminals mounted on said support, a lmember mov-jj ably mounted on said support, a conductor..4

'connectedftosaid terminals and put und-er tension by the movement of said'member, a

lmirror carried said conductor and a rtension device mounted adjacent said terminals the conductor under tension.

49. In -an oscillograph, a reflecting Agalvan'om'eeter comprising a support, terminals and a tension' device` mounted at the same end of vsaid support, a looped conductor with its ends connected tosaid terminals, a mirror carried by'said conductor, and a movable member in enga ment with said conductor connected to sai tension device andmovable thereby away from said terminals to put the conductor under tension.

5 0. In'an oscillograph, a reflecting galvanometer compris-ing a support, terminals and a tension device mounted on one side of said for yieldingly moving said lmember to p-u-t support, a member connected to said device and mounted to be moved away from the other side of said support by said device, a conductor looped around said member and having its ends secured to said terminals, and a mirror carried by said conductor.

51. In an oscillograph, a reflecting galvanometer comprising a support, terminals securcd to said support, a rod extending perpendicularly through said support adjacent said terminals and mounted to move longitudinally away from said terminals, a device secured to said support for yieldingly moving said rod longitudinally away from said terminals, a looped conductor supported by said rod with its ends secured to said terminals, and a mirror carried by said conductor.

52. An oscillograph provided with a tense conductor carrying a light mirror carried on a support removable from the magnetic field, said support and conductor being so related that a free space is provided about the mirror which is large relatively to the mirror and its support to permit ease of repair.

53. ln an oscillograph, a reflecting alvaiiometer comprising a magnet, a con uctor in the field of said magnet, a support for holding said conductor under tension between two points and cut away between said points to leave a relatively large space around the conductor to permitirse access to all sides of the conductor, and a mirror secured to said conductor between said points.

54. In an oscillograph, a reflecting galvanometer comprising a magnet having pole pieces for producing an intense magnetic field, a support adjacent said pole pieces, a conductor mounted on said support between said pole pieces, said support and said pole pieces being relatively vmovable both transversely and longitudinally of the axis of the pole pieces to permit access to the conductor, and a mirror carried by said conductor.

55. In an oscillograph, a reflecting galvanometer comprisin a magnet, a casing mounted adjacent t e poles of said magnet, pole pieces in said casing, a support removably mounted in said casing to permit said support to be moved both transversely and longitudinally of said casing, and a looped conductor on said support arranged to extend between said pole pieces when said support is in normal position whereby said conduotor may be removed from between said pole pieces before said support is withdrawn longitudinally from said casing.

In witness whereof I have hereunto set my hand this 11th day of March, 1905.

' LEWIS T. RBINSON. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

